Self centering rifling head



May 23, 1933.

G. W. MCCUNE SELF GENTERING RIFLING HEAD Filed May 28. 192s Z2 Hd 2Sheets-Sheet l Patented May 23, 1933 UNITED s'mras lAir'salia orticaGEORGE w. MccUNE, or BRIDGEPQRT, CONNECTICUT, AssIeNoa or ONE-HALF rroyJOHN A. CORNELL, orvisainei'iroar, coNNEcricnT f' SELF CENTERING RFLINGHEAD .Application filed May 28, 1928. Serial/No. 281,156.

This invention relates to a riflinghead and has for an object to providean improved head of this character which will automati cally adjustitself to variations in the diameter of the bore of the gun and willautomatically maintain the centerof the head in the center of the bore,so that the ritling will be uniform throughout the full length lof thebore and will also be uniform through out the circumference of the bore.

It is also an object of the invention to provide a rifling head withwhich all the rifiing grooves may be cut simultaneously throughout theentire periphery of the bore.

It is another object .of the invention to provide an improved means foradjusting the cutters to secure a greaterrange of adjustment, and inwhich the cutters will be simultaneously adjusted.

llith the foregoing and other objects in view, the invention consists incertain novel features of construction, combinations and arrangements ofparts as willbe more fully described in connection with the accompanyAing drawings. In these drawings,

Fig. 1 is a longitudinal section through the hea v Fig. 2 isan endelevation looking from` the left of Fig. 1 with the enclosing housingremoved and a portion of the front plate broken away to more clearlyshow the construction. Y

Fig. 3 is a transverse section substantially on line 3-3 of Fig. 1.

Fig; 4 is a partial side elevation looking toward the left of Fig. 2. v

Fig. 5 is a detailelevation of a portion of the front plate of Fig. 2showing the cut` ters extended in cutting posit-ion. L

Fig. G is a front 'elevation with the front head or plate removedshowing how the device is arranged for riliing a relatively small bore.

the cutter'adjusting means, and Y Fig. 8 is a perspective view ofone-half of the adjusting means of Fig. 7. i In rilling guns,particularly large guns, it is very diflicult to cut the grooves uni-Fig. 7 is a partial front view similar ,to Fig. showing a modifiedconstruction offormly due tok changes in temperature lof the gun andalso thev riiling tools. Also any variation in the size of the bore willcause ununiformrifling. The common practice is to provide a brasscylindrical block on the rifling head carrying the cutting tools whichis supposed to fit the boreof the gun, but

gun due to the increase of temperature or other variation will permitthe head to drop so that its axis is below the center line of the bore,and therefore, the rifling grooves will not be cut of a uniform depth.To overcome this -objection l have produced a construction of head whichwill automaticallyvadjust itself to Variations in the diameter of thebore and will thus automatically center itself so as to maintain'itsaxis always on thecenter line of the bore, and thus will cut, therifling grooves uniformly throughout the length of the bore and alsothroughout the periphery thereof. l have also probored, and whichcarries the rifling head.,

This head as shown, comprises a cylindrical central threaded into theend of the bar 10 and also into a ring or head 12 vwhich is securedtothe flange 13 of the bar 10 by meansof a plurality of screws 1li.Mounted on the cylindrical portion of the member 11 is an adjustingmember 15 which is preferably a continuous member and has a cylindricalbore fitting the member 11 and on which it is .slidable longitudinally.This adjusting member 15 has one or more conical surfaces in thelpresent construction two of them 16 and 17, which form cam surfaces foradjusting the intermediate members 18 and 19 respectively. These interfmediate members are shown as segmental members 1n four parts, in otherwords there or Vbody member 11 which isYV v it will be apparent that anexpansion of the are four segments on each of the conical surfaces 16and 17 although aV greater or less number may be used if foundpreferable. The inclined cam surfaces 16 and 17 may be continuousconical surfaces but it is preferred to provide inclined flats 20thereon cooperating with similarly inclined flats 21 on the segmentalmembers, as this arrangement is less likely to bind than would be acontinuous conical surface.v The elements 18 and 19 are enclosed byA aresilient cylindrical shell or casing 22 which is slit at one side andoverlapped to prevent entrance of chips, as shown at 23, so that it mayexpand or contract. Its tendency, however, is to expand and fit theVsurface of the boref The body memb-er 11 has a flange 24 at its innerend, and the members18 and 19 are Aheld against longitudinal movement bythis flange andthe head or ring 12. V

Resilient means is providedwhich tend to shift the adjusting member 15longitudinally of the kmember 11 to force the cam surfaces 16 and 17against the members 18 and 19 andthus tend to force them outwardlyagainst thev casing 22, andrtherefore, expand this casing. Thisresilient means in the construction shown comprises a plurality ofcoiled springs 25 seated at their opposite ends in sockets in theopposed ends of the members 12 and 15. VAny suitable number of thesesprings may be employed, preferably equally spaced around the member 15.Their outer ends may rest against plates 26 engaging adjusting screws 27vby means of which the tension of the springs may be adjusted Means isprovided for limiting the ex# andinO movement of the casing 22. At P e rits outer end a ring 28 isthreaded on the flange 13 and has a reducedlateral extension 29 engaging the end of the'V casing 22. This reducedextension is threaded, as

shown at 30, for a sizing nut or ring 31 which has a beveled inner end32 cooperating with a similar bevel formed on the end of the casing 22.These rings are provided with sockets 33 to receive spanner wrenches foroperating these rings. At the opposite end the casing 22 has a similarand opposite bevel 34 cooperating with a similar-bevel on a plate orring 35 secured to the flange 24 of the member 11 byany suitable means,such as screws 36. It will be Aapparent that by adjusting nut 28 thecasing 22 will be forced toward or allowed to recede from the ring35,and then the nut orring 31 may be adjusted against the bevel ofthecasing 22 to prevent thisV end expanding a greater amount than theYopposite end against the ring 35, thus maintaining the casing thesamesize throughout,and these beveled surfacespreve-nt the casing 22expanding beyond a certain maxi-V mum limit. The casing 22 is made to agreater diameter than that of the bore of the gun, say aboutthree-sixteenths of an inch. Then a longitudinal strip is cut out of itat one side and'it is then compressed, ground and lapped to size.

The cutting tools for cutting the spiral grooves ofthe rifle arecarried'at the forward or inner end of this head. The plate 35 isprovided. withla plurality of radial clove-tailed slots 37 in which aremounted carriers 38 forK the cutters 39, and these carriers havedove-tailed ribs 40 on their back walls sliding in the dove-tailedgrooves 37 so that these carriers are guided for radial movement in thering 35. lThe cutters 39 may each have one or more 'cutting edges forcutting the rifling grooves.` In theforin shown in Fig. 2 each cutterhas three cutting edges 41 so that each cutter will cut three grooves.Vln the form shown in Fig. 6 each cutter has only two cutting edges, butit will be vunderstood that they may each vhave one or more cuttingedges as is found desirable. The body of the carrier is recessed as'indicated at 42, to receive the cutters 39, and thecutters maybe securedthereto by any suitable means, such as-screws 43 and properly located bydowel pins 44.

Mounted on the inner end of the member 11 is a guiding stud 45, and'itmay be mounted in the member 11 by threading it into the same, asindicated at 46. This stud 45 provides a support and guide for adjustingblock 47 which is fmounted to slide longitudinally in the member 45.This block is provided with an inclined peripheral grooveprovidinginclined or conical surfaces 48 and 49 which are paralleltoeachother and bear on the opposite sides of an extension 50`on each ofthe carriers 38, and this extension has inclined walls on its oppositesides corresponding to the inclination of the walls 48 and 49.v It willbe apparent from this construction that ifthe block 47 is forced to theright, as viewed in- Fig. 1, the carriers 38 and the cutters 39 will beforced laterally outwardly by coaction of the 'inclined surface 49 withthose of the extensions 50, while if the block 47 is forced to the left,as viewed in Fig. 1, the inclined surface 48 will have a camming actionon the other side of .the extensions 50 and will draw the carriers 38and the cutters 39 radially inwardly, and therfore, the positions-of thecuttingedges 41l of all the cutters may be simultaneously adjusted andfor equal` amounts by shifting camming surfaces 48 and V49 together withthe cooperating surfaces on the extensions in Fig. l, and these cutterswould be drawn v inwardly by shifting block 47 to the right.

Clamped against the outer surface of the ring 35 is a plate or guidinghead 52 which is threaded onto the end of the stud 45, as shown at 53,and by which it may, thereforeybe clamped against the surface of theAring 35. The outside diameter of this plate or head is approximately thediameter of the bore to be rified and serves as a guiding means to guidethe head into the bore when the head is inserted in the bore to startthe rifling operation, and thus protects the cutters 39 and properlypositions them Vrelative to the bore of the gun for the beginning of theriding operation' The outer rim of the member 52 may be provided withribs 54 to cooperate with a suitable tool for properly screwing thishead onto the head or unscrewing it` therefrom, and clamping it againstvthe ring'35.

The means for adjusting the block 47 may take different forms but thatshown in the drawing is a very effective one. In this 'arrangement asshown the plate 52 has an eX- tension or support 55 carrying anadjusting screv. 56 which is supported at its opposite end in the bodyof the member 52 and has threaded engagement with a nut 57 which is heldagainst rotation by a pin-58. The nut 57 has a notch 59 inlits outeredge cooperating with a holding pawl 60 `pivotally mounted on a slidingpin 6l connected to the block 47 and a spring 62 normally tends to holdthe pawl 60 in the notch in the nut 57. The adjusting screw 56 may beprovided with a suitable calibrated gauge 63 to indicate the amount ofadjustment. The bloclz'47 may be shifted manuallyto contract or collapsethe cutters 39 by means of a rod 64 connected to the block and slidablein the head 52. This rod has a connecting .39 their radial movementsandalsoto prevent entrance of chipsinto the adjusting' mechanism. The innerwallv of the head`52 is recessed and carries an annular clamping member69 which is guided for lateral movements on a cylindrical shoulder 70.The

- ring 69 is held against turning movements by a key: Iliandfit is'threaded on its outerr wall, as shown at .72, for threaded vengagementwith an adjusting4 ring 73 which fills the space between the head 52,the cutters 39 l r and the front face of the ring 35. This ring 7 3 hassocketsl 74 for insertion of a spanner wrench or other suitable too-lforrotating this ring.k By turning this lring-the clamp'- ingring 69 isAadjusted to give the proper.

pressure on'the cutters 39 to assist in holdingl them in proper positionland prevent their chattering but it should be sufficiently loose whenshifting the block `47 to ypermit the cutters 39 to be' moved radiallyunder the action of the adjusting block 47. After adjustment the ring69vv maybe tightly clamped against the-cuttersf39 tohold them prevent''chattering in proper position and during the cutting stroke.

The operation is as follows: As indicated the head or plat'e52f will`guide the 'device into the bore of the gun and prevent injury to thecutters or the gun by positioning` the head central in the bore. Afterthe pawl 6()` is seated in the nut 57 the adjusting screw 56 is turnedto bring the cutters 39 in proper position for the first cut and thonthe head I is forced through the gun'in the usualmenner to cutthe riiinggrooves, and it will'be apparentthat suilicient cutters maybe carried`by thishead to simultaneously Vout all of the grooves. 'At the end lofthe inward movementy of the head the pawl 60 may be releasedy fromthenut 57 and then the op erator by manipulating the lever 'may shift theblock 47 to lthe left as viewed in Fig. l, which will cause. theinclined wallsv 48 coacting with the extensions 50 oni the cuttercarriers 38 to draw the cutters inwardly to the full' line position ofFig. 1,.; so that the head may be withdrawn from the bore for the 'nextoperation. lAfter the head is drawn back tothe inlet end, the lever 65is manipulatedto force the block 47 to the right which will force thecutters out-l wardly. The p'awl 60vis again seated in the notch 59 inthe nut 57 to hold the bloclr147 and therefore, the cutters 39 in properposition. The adjusting screw 56 may be rotated to force the block47,inwardly or to the right as viewedzinFig. l, to force the cuttersoutwardly the proper amount for the next step which may be accurately'determined by the this bore dueto changes in temperature'or otherreasons. This is accomplishedl bythe members 15, 18, l9and 22andcooperating elements.v Thesprings 25 tend to force the adjusting member15 to ther left, as shown lO ranged about the member 11 and are pressedagainst the inner surfaceof the resilient split casing 22. They,therefore,-expand this casing so that itsl outer surface always fits thesurface ofthe bore of the gun. The out-k lU ward or expanding movement,however, is

limited by the beveled surfaces 32 land 34 at the opposite ends of thiscasing, and as indicated above this maximum expansion may be adjustedfor the maximum bore of the 219 gun by manipulation of the wing nuts' 28and 31. As the head moves through the bore of the gun the casing 22 isheld snugly against the surface of the bore, as indicated by the actionof the springs 25.

cause of contraction of thegun walls by reduction in temperature thesurface ofthe bore will press the casing 22 inwardly to correspond withthe size of the bore and 39 against the action of the spring 25, butduring the expansion and contraction of the casing 22 the center of thehead will always correspond with the center of the bore due to thepeculiar arrangement of the elements,

35 Tand therefore, the head is always automatically centered in the boreand the rifiing cutters 39 are all uniformly and pro erlypositioned.throughout the periphery o the head, and the rifling groovesare all cut to a Z4O'uniform depth throughout their entire length.

The head as shown in Fig. l, is for a relatively large gun. Fig. 6 showshow the same principal may be used for iiiling a 4,5 relatively smallgun. In this arrangement each carrier 38 supports a cutter 75 havingonly two cutting edges 41, or the cutter may have only one cutting edgeas desired, and as the sides 76 of this cutter may be "arranged`parallel to each other and radially of the head I am enabled to securemaxi mum adjustment.

In Figs. 7 and 8, I have shown an adjusting block 77 to take the placeof the block 5547, Fig. 1, of somewhat different construction. Thisblock, however, is lnot as desirable as the block 47 because it is moreex pensive to make and does' not permit as great'a range of adjustmentasY the block 47 It is a conical block provided with'T-shaped slots 78in its outer inclined surfacejin 'which similar T-shaped extensions79.1on carriers` corresponding to the carriers 48 for the cutters areguided. g Thus as the block 77 is 65 shifted the same as the block 47these Should a a5 4portion ofthe bore be somewhat smallerbe- 1., In aYrifiing head, a cylindrical bodyv member,a continuous member having acylindrical bore mountedV to slide longitudinally on the body-member, aplurality of segments, outside the continuous member, co acting camsurfaces on the continuousmember and said segments, resilient meanstending to shift thevcontinuous member to shift the segmentsoutwardly,and a split casing embracing the segments adapted to lit thebore of a gun and held in engagement therewith by said segments.

2. In arifling head, a cylindrical body member, an adjusting memberhaving a bore to fit the body member and slidable longitudinallythereon, a plurality of segments j outside the adjusting member,cooperating cam surfaces on the adjusting member and the segments,asplit resilient casing embracing the segments, and one or more springstending to shift the adjusting member to expand said casing to fit thebore of a gun and center the head therein.

3. Ina rifling head, a Vcylindrical guiding member, an adjusting memberhaving a cylindrical bore to lit that of the guiding member and slidablelongitudinally thereon, said adjusting member being provided with camsurfaces inclined to the axis of the head, a plurality of laterallymovable members engaging said cam surfaces, one or more springs tendingto shift the adjusting member to move the .laterally movable membersoutwardly, a split resilient cylindrical casing enclosing said laterallymovable members radapted to iit the bore'of a gun and held in engagementtherewith by said members, and lcutters carried by sai head.

4. In a riiiing head, a cylindrical guiding member, an adjusting memberhaving a cylin drical bore to fit that ofthe guiding member and slidablelongitudinally thereon, said adjusting member beingv provided with camsurfaces inclined to the axis of the bead, a plurality ofy laterallymovable members engaging said cam surfaces, one or more springs tendingto shift the adjusting member to force the laterally movable membersoutwardly, a split resilient cylindrical casing enclosing saidlaterally'movable mem bers and adjusted thereby to lit the bore of agun, and adjustable means for limiting the expansion of said casing.

5.1Ina rifling head, a cylindrical guidy ing member, an adjusting memberhaving a Vcylindrical bore to fit that of the guiding member andslidable longitudinally thereon,

ber to force the laterally movable members outwardly, a split resilientcylindrical casing enclosing said laterally movable members and adjustedthereby to fit the bore of a gun, adjustable means for limiting theexpansion of said casing, a plurality of cutters carried by said head,and means for si-A multaneously adjusting said cutters.

6. In a rifling head, an expansible cylindrical casing to fit the boreof the gun, an adjusting member movable longitudinally of the head andhaving cam surfaces inclined to the axis of the head, a plurality ofsegments enclosed by the casing and located between said casing and theadjusting member, said segments being capable of radial movement underaction or said cam surfaces, resilient means tending to shift theadjusting member to force said segments outwardly to expand the casing,means to maintain said adjusting member concentric with the axis of thehead, and a plurality of cutters carried by the head.

7. In a rifling head, an expansible cylindrical casing tofit the bore ofthe gun, an adjusting member movable longitudinally of the head andhaving cam surfaces inclined to the axis of the head, a plurality ofradially movable members between the adjusting member and the casing andarranged to be shifted by the action of said cam surfaces, resilientmeans tending to shift the adjusting member to expand the casing,adjustable means to limit the expansion of the casing, a plurality ofcutters carried by the head, and means for simultaneously adjusting thecutters radially of the head.

8. In a riling head, means for guiding the head in the bore of a gun, aplurality of radially movable cutter supports carried by said head, anadjusting block movable longitudinally of the head, cooperating means onthe block and the supports to shift the supports by movement of theblock, an adjusting screw, a nut operated by said screw, a detachableconnection between the nut'and the block to hold the block in a givenposition depending on the position of the nut, and independent means forshifting the block to shift the cutter supports when said connection isdisconnected.

9. In a rifling head, means for guiding the head in the bore of a gun,radial guides, cutter supports in said guides, riiing cutters carried bysaid supports, a head forwardly of said cutters, a clamping ring mountedfor sliding movement on said head and adapted to engage and guide thecutters, and an adjusting ring closing the space between the head andthe cutters and having threaded engagement with vthe clamping ring toadjust the same toward and from the cutters in' a1 direction laxially ofthe head to :clamp the cutters in adjusted positions and torelease them.

10. In a rilling head, means movable withy the head for automaticallymaintaining the' axis ofthe head in the center of the bore regardless ofchanges in the sizes of the bore, comprising a split resilient casingfree to expand and contract and tending to expand so as to lit the boreregardless of changes Yin the diameter thereof, and self acting meansenclosed by said casing free to expand and contract with the casing,means for mounting said latter means so that it is always coaxially withthe head for automatically maintaining the casing coaxial with the axisof the head, and rifling cutters carried by said head.

ll. In a rifling head, a split resilient casing free to expand andcontract to fit the bore of the gun and movable with the head,

an adjusting means enclosed by said casing adapted to expand the casing,resilient means tending to shift the adjusting meansv to expand thecasing and automatically maintain it the size of the bore,'meansconcentric with the axisof the khead for mounting said adjusting means,and a series of gutters for riliing grooves carried by said ead. V

l2. In a head for rifling the bore of a gun, a split resilient casingadapted to expand and contract so as to fit the bore of the gun in spiteof variations in the size of, this bore Vand movable with the head,resilient means tending to expand the casing to automatically maintainit the size of the gun bore, a plurality ofl cutters for simultaneouslycutting a pluralityk of rifling grooves in the bore carried by saidhead, and means for simultaneously adjusting the cutters radially of thehead.

13. In a head for rifling the bore of a gun, a split resilient casingmovable with the head and adapted to expand and con-k tract so as to atall timesl fit thebore of the gun, an adjusting means enclosed by saidcasing, resilient means tending to shift the adjusting means to expandthe casing and automatically maintain it the same size as the gun bore,means to maintain the casing always concentric with the axis of thevhead, a plurality ofcutters carried by the head adapted tosimultaneously cut a plurality of rifling grooves in the bore, and meanssimultaneously adjusting the cutters radially of the head.

14. In a head for rifling the bore of a gun, a resilient split casingmovable with the head and adapted to expand and contract so as to at alltimes lit the bore of the gun, rey silient means tending to expand .thecasing to automatically maintain it the same size as the bore,adjustable; means to engage the casing to limit the expansion of thecasing, L plurality of cutters Carried by the .head adapted tosimultaneously cut a plurality of fillingY grooves in the bore, andlueunsffor` simultaneously adjusting said cutterslrvadially of the head.

Irl-testimony whereof I ax my signature.

` GEORGE W. MCCUNE.

